Fuel processing reactor with internal heat exchange for low pressure gas stream

A compact fuel processing reactor. The reactor includes a housing having an inlet for receiving a process gas and an outlet for a directing a product gas out of the housing. A catalyst bed that includes discrete particles of a refractory material is located within the housing for contacting the process gas. A coiled tubing heat exchanger is at least partially disposed within the catalyst bed for cooling the catalyst bed. The coiled tubing can comprise a smooth continuous outer surface in intimate contact with the discrete particles. The circulating cooling medium comprises water in liquid, gas or a mixture of liquid and gas phases. The discrete particles in the catalyst bed are in intimate contact with at least a portion of the coiled tubing to promote heat transfer from the catalyst bed to the coiled tubing. The heat exchanger has less than about 25, preferably less than about 20, more preferably less than about 15, and still more preferably less than about 10 square meters of heat exchanging surface area per cubic meter of catalyst bed. The catalyst bed can be a water gas shift, desulfurization or reforming bed. The reactor can include one or more additional catalyst beds arranged in series such that the housing enclosed a shift catalyst bed as well as a desulphurization bed and/or a reforming bed. Methods of cooling a catalyst bed within a compact reactor and methods of manufacturing a compact reactor are also provided.